Accompanying the recent spread of personal computers in households, digital still cameras capable of inputting image data such as photographed scenes and portraits into personal computers are rapidly becoming available. In addition, many cellular telephones and smart phones are being equipped with camera modules for inputting images. Imaging elements such as CCD's and CMOS's are employed in these devices having photography functions. Recently, miniaturization of these imaging elements is advancing, and there is demand for miniaturization of the entirety of the photography devices as well as imaging lenses to be mounted thereon. At the same time, the number of pixels in imaging elements is increasing, and there is demand for high resolution and high performance of imaging lenses. Performance corresponding to 5 megapixels or greater, and more preferably 8 megapixels or greater, is desired.
In response to such demands, an imaging lens having a five lens configuration, which is a comparatively large number of lenses, may be considered in order to shorten total length and to obtain high resolution. For example, imaging lenses constituted by a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, a fourth lens having a negative refractive power, and a fifth lens having a positive refractive power have been proposed in Japanese Unexamined Patent Publication No. 2011-085733, Chinese Utility Model Publication No. 202110325, U.S. Pat. No. 7,274,515, Japanese Unexamined Patent Publication No. 63 (1988)-116112, and Japanese Unexamined Patent Publication No. 63 (1988)-274904, as well as in Japanese Patent Application No. 2011-133062 assigned to the present assignee.